Import risk analysis: Llamas (Lama glama) and alpacas (Vicugna ...

14. Foot and mouth disease virus
14.1. HAZARD IDENTIFICATION
14.1.1. Aetiological agent
Family: Picornaviridae; Genus: Aphthovirus; Species: Foot and mouth disease virus
(FMDV). There are seven serotypes of the virus: O, A, C, SAT 1, SAT 2, SAT 3, and Asia
1 (Stanway et al 2005).
14.1.2. OIE list
Listed as a disease of multiple species.
14.1.3. New Zealand status
Listed on the Unwanted Organisms Register as an exotic notifiable disease.
14.1.4. Epidemiology
Extensive reviews on foot and mouth disease are available (Sanson 1994; Thomson &
Bastos 2004) and much of the information given below is taken from these. The disease
has been eradicated from, or has not occurred in, countries relevant to this risk analysis
except for South American countries. It can infect all cloven hoofed animals and is
considered to be the most contagious and economically devastating animal disease. The
outbreaks of the disease in Britain in 2001 (Thompson et al 2002) and in Taiwan in 1997
(Yang et al 1999) cost those countries billions of dollars.
Infected animals excrete the virus in saliva, faeces, urine, milk, semen, ocular and nasal
discharges (Sanson 1994; Thomson & Bastos 2004), and virus is also discharged in aerosol
in expired air. The incubation period is usually 2-14 days (Sanson 1994). Viraemia usually
continues from 1 day before until 11 days after signs of disease first appear. Transmission
can be from direct contact, contact with infected fomites, ingestion of infected animal
products or from inhaling aerosolized virus (Sanson 1994; Thomson & Bastos 2004).
Long- term carriers excrete small amounts of virus from the pharynx. Cattle may excrete
virus in this way for up to 3 years. However, the amount of virus excreted by persistent
carriers is low and the ability of persistently infected cattle to spread the disease is
controversial (Thomson & Bastos 2004).
Camelids are susceptible to foot and mouth disease. However, several investigations
indicate that they are much more resistant to the infection than cattle, carry the virus for
only short periods and are not highly infectious (Fowler 1992; David et al 1994; Viera et al
1995; Wernery & Kaaden 2002; Wernery & Kaaden 2004). According to Fowler (1992)
Mancini infected South American camelids experimentally and was able to transmit the
disease by injection into the epidermis of the tongue, intramuscular and intravenous
injection and by cohabitation. The first lesions developed 48-72 hours after infection.
Some llamas infected intramuscularly or intravenously died but transmission by
cohabitation was not always successful. It was concluded that camelids are less susceptible
than cattle and sheep. In another study only two out of 10 llamas developed slight lesions
when placed in contact with infected pigs and infected llamas carried the virus in the
oesophageal-pharyngeal region for only short periods compared to cattle (David et al
46 ● Import risk analysis: Llamas and alpacas from specified countries MAF Biosecurity New Zealand